2zvv
From Proteopedia
Crystal structure of Proliferating cellular nuclear antigen 1 and Short peptide from human P21
Structural highlights
Function[PCNA1_ARATH] This protein is an auxiliary protein of DNA polymerase delta and is involved in the control of eukaryotic DNA replication by increasing the polymerase's processibility during elongation of the leading strand (By similarity).[HAMAP-Rule:MF_00317] [CDN1A_HUMAN] May be the important intermediate by which p53/TP53 mediates its role as an inhibitor of cellular proliferation in response to DNA damage. Binds to and inhibits cyclin-dependent kinase activity, preventing phosphorylation of critical cyclin-dependent kinase substrates and blocking cell cycle progression. Functions in the nuclear localization and assembly of cyclin D-CDK4 complex and promotes its kinase activity towards RB1. At higher stoichiometric ratios, inhibits the kinase activity of the cyclin D-CDK4 complex.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe proliferating cell nuclear antigen (PCNA) is well recognized as one of the essential cellular components of the DNA replication machinery in all eukaryotic organisms. Despite their prominent importance, very little biochemical and structural information about plant PCNAs is available, in comparison with that obtained from other eukaryotic organisms. We have determined the atomic resolution crystal structures of the two distinct Arabidopsis thaliana PCNAs (AtPCNA), both complexed with the C-terminal segment of human p21. Both AtPCNAs form homotrimeric ring structures, which are essentially identical to each other, including the major contacts with the p21 peptide. The structure of the amino-terminal half of the p21 peptide, containing the typical PIP box sequence, is remarkably similar to those observed in the previously reported crystal structures of the human and archaeal PCNA-PIP box complexes. Meanwhile, the carboxy-terminal halves of the p21 peptide in the plant PCNA complexes are bound to the protein in a unique manner, most probably because of crystal packing effects. A surface plasmon resonance analysis revealed high affinity between each AtPCNA and the C-terminal fragment of human p21. This result strongly suggests that the interaction is functionally significant, although no plant homologs of p21 have been identified yet. We also discovered that AtPCNA1 and AtPCNA2 form heterotrimers, implying that hetero-PCNA rings may play critical roles in cellular signal transduction, particularly in DNA repair. Crystal structures of the Arabidopsis thaliana proliferating cell nuclear antigen 1 and 2 proteins complexed with the human p21 C-terminal segment.,Strzalka W, Oyama T, Tori K, Morikawa K Protein Sci. 2009 May;18(5):1072-80. PMID:19388052[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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